Frequency modulation and magnetic resonance in electric resonators

Most reported negative index of materials (NIMs) have combined conducting split ring resonators (SRRs) to realize the magnetic response and nonresonant wires to realize the electric response. But wire media has some disadvantages in common practice. Therefore, electric resonators were introduced by researchers to replace the wire media recently. Electric resonators are convenient to control and can be made relatively insensitive to the cell-to-cell coupling. The electric resonance frequency of the resonators is related to the lattice constant of the structure. Then, using finite element simulation and making magnetic field is perpendicular to the plane of metamaterial, the results can be obtained for varying lattice constant. In each case, the permittivity is retrieved from the simulated S parameters. The electric-resonance frequency increases and the frequency range of negative permittivity cut short when the lattice constant decrease. In addition, there is magnetic resonance in some electric resonators, which can be used to realize the negative permeability.